"I'm definitely not going to get married in latex," she tells PEOPLE of one rampant rumor. "When I wear latex onstage, I sweat. I could wring out those dresses – and I don't want to do that at my wedding."

The singer, 25 – whose second album, Teenage Dream drops Aug. 24 – does, however, use her wardrobe to communicate her feelings about her fiancé.